diff options
Diffstat (limited to 'lib/avb/libavb/avb_slot_verify.c')
| -rw-r--r-- | lib/avb/libavb/avb_slot_verify.c | 1188 |
1 files changed, 1188 insertions, 0 deletions
diff --git a/lib/avb/libavb/avb_slot_verify.c b/lib/avb/libavb/avb_slot_verify.c new file mode 100644 index 0000000..d00b9b9 --- /dev/null +++ b/lib/avb/libavb/avb_slot_verify.c @@ -0,0 +1,1188 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "avb_slot_verify.h" +#include "avb_chain_partition_descriptor.h" +#include "avb_footer.h" +#include "avb_hash_descriptor.h" +#include "avb_kernel_cmdline_descriptor.h" +#include "avb_sha.h" +#include "avb_util.h" +#include "avb_vbmeta_image.h" +#include "avb_version.h" +#include <common.h> + +/* Maximum allow length (in bytes) of a partition name, including + * ab_suffix. + */ +#define PART_NAME_MAX_SIZE 32 + +/* Maximum number of partitions that can be loaded with avb_slot_verify(). */ +#define MAX_NUMBER_OF_LOADED_PARTITIONS 32 + +/* Maximum number of vbmeta images that can be loaded with avb_slot_verify(). */ +#define MAX_NUMBER_OF_VBMETA_IMAGES 32 + +/* Maximum size of a vbmeta image - 64 KiB. */ +#define VBMETA_MAX_SIZE (64 * 1024) + +/* Helper function to see if we should continue with verification in + * allow_verification_error=true mode if something goes wrong. See the + * comments for the avb_slot_verify() function for more information. + */ +static inline bool result_should_continue(AvbSlotVerifyResult result) { + switch (result) { + case AVB_SLOT_VERIFY_RESULT_ERROR_OOM: + case AVB_SLOT_VERIFY_RESULT_ERROR_IO: + case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA: + case AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION: + return false; + + case AVB_SLOT_VERIFY_RESULT_OK: + case AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION: + case AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX: + case AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED: + return true; + } + + return false; +} + +static AvbSlotVerifyResult load_and_verify_hash_partition( + AvbOps* ops, + const char* const* requested_partitions, + const char* ab_suffix, + bool allow_verification_error, + const AvbDescriptor* descriptor, + AvbSlotVerifyData* slot_data) { + AvbHashDescriptor hash_desc; + const uint8_t* desc_partition_name = NULL; + const uint8_t* desc_salt; + const uint8_t* desc_digest; + char part_name[PART_NAME_MAX_SIZE]; + AvbSlotVerifyResult ret; + AvbIOResult io_ret; + uint8_t* image_buf = NULL; + size_t part_num_read; + uint8_t* digest; + size_t digest_len; + const char* found; + + if (!avb_hash_descriptor_validate_and_byteswap( + (const AvbHashDescriptor*)descriptor, &hash_desc)) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + desc_partition_name = + ((const uint8_t*)descriptor) + sizeof(AvbHashDescriptor); + desc_salt = desc_partition_name + hash_desc.partition_name_len; + desc_digest = desc_salt + hash_desc.salt_len; + + if (!avb_validate_utf8(desc_partition_name, hash_desc.partition_name_len)) { + avb_error("Partition name is not valid UTF-8.\n"); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + if (!avb_str_concat(part_name, + sizeof part_name, + (const char*)desc_partition_name, + hash_desc.partition_name_len, + ab_suffix, + avb_strlen(ab_suffix))) { + avb_error("Partition name and suffix does not fit.\n"); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + image_buf = avb_malloc(hash_desc.image_size); + if (image_buf == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } + + io_ret = ops->read_from_partition(ops, + part_name, + 0 /* offset */, + hash_desc.image_size, + image_buf, + &part_num_read); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_errorv(part_name, ": Error loading data from partition.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto out; + } + if (part_num_read != hash_desc.image_size) { + avb_errorv(part_name, ": Read fewer than requested bytes.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto out; + } + + if (avb_strcmp((const char*)hash_desc.hash_algorithm, "sha256") == 0) { + AvbSHA256Ctx sha256_ctx; + avb_sha256_init(&sha256_ctx); + avb_sha256_update(&sha256_ctx, desc_salt, hash_desc.salt_len); + avb_sha256_update(&sha256_ctx, image_buf, hash_desc.image_size); + digest = avb_sha256_final(&sha256_ctx); + digest_len = AVB_SHA256_DIGEST_SIZE; + } else if (avb_strcmp((const char*)hash_desc.hash_algorithm, "sha512") == 0) { + AvbSHA512Ctx sha512_ctx; + avb_sha512_init(&sha512_ctx); + avb_sha512_update(&sha512_ctx, desc_salt, hash_desc.salt_len); + avb_sha512_update(&sha512_ctx, image_buf, hash_desc.image_size); + digest = avb_sha512_final(&sha512_ctx); + digest_len = AVB_SHA512_DIGEST_SIZE; + } else { + avb_errorv(part_name, ": Unsupported hash algorithm.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + if (digest_len != hash_desc.digest_len) { + avb_errorv( + part_name, ": Digest in descriptor not of expected size.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + if (avb_safe_memcmp(digest, desc_digest, digest_len) != 0) { + avb_errorv(part_name, + ": Hash of data does not match digest in descriptor.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION; + goto out; + } + + ret = AVB_SLOT_VERIFY_RESULT_OK; + +out: + + if (ret == AVB_SLOT_VERIFY_RESULT_OK || result_should_continue(ret)) { + /* If this is the requested partition, copy to slot_data. */ + found = avb_strv_find_str(requested_partitions, + (const char*)desc_partition_name, + hash_desc.partition_name_len); + if (found != NULL) { + AvbPartitionData* loaded_partition; + if (slot_data->num_loaded_partitions == MAX_NUMBER_OF_LOADED_PARTITIONS) { + avb_errorv(part_name, ": Too many loaded partitions.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + loaded_partition = + &slot_data->loaded_partitions[slot_data->num_loaded_partitions++]; + loaded_partition->partition_name = avb_strdup(found); + loaded_partition->data_size = hash_desc.image_size; + loaded_partition->data = image_buf; + image_buf = NULL; + } + } + +fail: + if (image_buf != NULL) { + avb_free(image_buf); + } + return ret; +} + +static AvbSlotVerifyResult load_and_verify_vbmeta( + AvbOps* ops, + const char* const* requested_partitions, + const char* ab_suffix, + bool allow_verification_error, + AvbVBMetaImageFlags toplevel_vbmeta_flags, + int rollback_index_location, + const char* partition_name, + size_t partition_name_len, + const uint8_t* expected_public_key, + size_t expected_public_key_length, + AvbSlotVerifyData* slot_data, + AvbAlgorithmType* out_algorithm_type) { + char full_partition_name[PART_NAME_MAX_SIZE]; + AvbSlotVerifyResult ret; + AvbIOResult io_ret; + size_t vbmeta_offset; + size_t vbmeta_size; + uint8_t* vbmeta_buf = NULL; + size_t vbmeta_num_read; + AvbVBMetaVerifyResult vbmeta_ret; + const uint8_t* pk_data; + size_t pk_len; + AvbVBMetaImageHeader vbmeta_header; + uint64_t stored_rollback_index; + const AvbDescriptor** descriptors = NULL; + size_t num_descriptors; + size_t n; + bool is_main_vbmeta; + bool is_vbmeta_partition; + AvbVBMetaData* vbmeta_image_data = NULL; + + ret = AVB_SLOT_VERIFY_RESULT_OK; + + avb_assert(slot_data != NULL); + + /* Since we allow top-level vbmeta in 'boot', use + * rollback_index_location to determine whether we're the main + * vbmeta struct. + */ + is_main_vbmeta = (rollback_index_location == 0); + is_vbmeta_partition = (avb_strcmp(partition_name, "vbmeta") == 0); + + if (!avb_validate_utf8((const uint8_t*)partition_name, partition_name_len)) { + avb_error("Partition name is not valid UTF-8.\n"); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + /* Construct full partition name. */ + if (!avb_str_concat(full_partition_name, + sizeof full_partition_name, + partition_name, + partition_name_len, + ab_suffix, + avb_strlen(ab_suffix))) { + avb_error("Partition name and suffix does not fit.\n"); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + avb_debugv("Loading vbmeta struct from partition '", + full_partition_name, + "'.\n", + NULL); + + /* If we're loading from the main vbmeta partition, the vbmeta + * struct is in the beginning. Otherwise we have to locate it via a + * footer. + */ + if (is_vbmeta_partition) { + vbmeta_offset = 0; + vbmeta_size = VBMETA_MAX_SIZE; + } else { + uint8_t footer_buf[AVB_FOOTER_SIZE]; + size_t footer_num_read; + AvbFooter footer; + + io_ret = ops->read_from_partition(ops, + full_partition_name, + -AVB_FOOTER_SIZE, + AVB_FOOTER_SIZE, + footer_buf, + &footer_num_read); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_errorv(full_partition_name, ": Error loading footer.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto out; + } + avb_assert(footer_num_read == AVB_FOOTER_SIZE); + + if (!avb_footer_validate_and_byteswap((const AvbFooter*)footer_buf, + &footer)) { + avb_errorv(full_partition_name, ": Error validating footer.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + /* Basic footer sanity check since the data is untrusted. */ + if (footer.vbmeta_size > VBMETA_MAX_SIZE) { + avb_errorv( + full_partition_name, ": Invalid vbmeta size in footer.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + vbmeta_offset = footer.vbmeta_offset; + vbmeta_size = footer.vbmeta_size; + } + + vbmeta_buf = avb_malloc(vbmeta_size); + if (vbmeta_buf == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } + + io_ret = ops->read_from_partition(ops, + full_partition_name, + vbmeta_offset, + vbmeta_size, + vbmeta_buf, + &vbmeta_num_read); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + /* If we're looking for 'vbmeta' but there is no such partition, + * go try to get it from the boot partition instead. + */ + if (is_main_vbmeta && io_ret == AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION && + is_vbmeta_partition) { + avb_debugv(full_partition_name, + ": No such partition. Trying 'boot' instead.\n", + NULL); + ret = load_and_verify_vbmeta(ops, + requested_partitions, + ab_suffix, + allow_verification_error, + 0 /* toplevel_vbmeta_flags */, + 0 /* rollback_index_location */, + "boot", + avb_strlen("boot"), + NULL /* expected_public_key */, + 0 /* expected_public_key_length */, + slot_data, + out_algorithm_type); + goto out; + } else { + avb_errorv(full_partition_name, ": Error loading vbmeta data.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto out; + } + } + avb_assert(vbmeta_num_read <= vbmeta_size); + + /* Check if the image is properly signed and get the public key used + * to sign the image. + */ + vbmeta_ret = + avb_vbmeta_image_verify(vbmeta_buf, vbmeta_num_read, &pk_data, &pk_len); + switch (vbmeta_ret) { + case AVB_VBMETA_VERIFY_RESULT_OK: + avb_assert(pk_data != NULL && pk_len > 0); + break; + + case AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED: + case AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH: + case AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH: + ret = AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION; + avb_errorv(full_partition_name, + ": Error verifying vbmeta image: ", + avb_vbmeta_verify_result_to_string(vbmeta_ret), + "\n", + NULL); + if (!allow_verification_error) { + goto out; + } + break; + + case AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER: + /* No way to continue this case. */ + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + avb_errorv(full_partition_name, + ": Error verifying vbmeta image: invalid vbmeta header\n", + NULL); + goto out; + + case AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION: + /* No way to continue this case. */ + ret = AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION; + avb_errorv(full_partition_name, + ": Error verifying vbmeta image: unsupported AVB version\n", + NULL); + goto out; + } + + /* Byteswap the header. */ + avb_vbmeta_image_header_to_host_byte_order((AvbVBMetaImageHeader*)vbmeta_buf, + &vbmeta_header); + + /* If we're the toplevel, assign flags so they'll be passed down. */ + if (is_main_vbmeta) { + toplevel_vbmeta_flags = (AvbVBMetaImageFlags)vbmeta_header.flags; + } else { + if (vbmeta_header.flags != 0) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + avb_errorv(full_partition_name, + ": chained vbmeta image has non-zero flags\n", + NULL); + goto out; + } + } + + /* Check if key used to make signature matches what is expected. */ + if (pk_data != NULL) { + if (expected_public_key != NULL) { + avb_assert(!is_main_vbmeta); + if (expected_public_key_length != pk_len || + avb_safe_memcmp(expected_public_key, pk_data, pk_len) != 0) { + avb_errorv(full_partition_name, + ": Public key used to sign data does not match key in chain " + "partition descriptor.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED; + if (!allow_verification_error) { + goto out; + } + } + } else { + bool key_is_trusted = true; + const uint8_t* pk_metadata = NULL; + size_t pk_metadata_len = 0; + + if (vbmeta_header.public_key_metadata_size > 0) { + pk_metadata = vbmeta_buf + sizeof(AvbVBMetaImageHeader) + + vbmeta_header.authentication_data_block_size + + vbmeta_header.public_key_metadata_offset; + pk_metadata_len = vbmeta_header.public_key_metadata_size; + } + + avb_assert(is_main_vbmeta); + io_ret = ops->validate_vbmeta_public_key( + ops, pk_data, pk_len, pk_metadata, pk_metadata_len, &key_is_trusted); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_errorv(full_partition_name, + ": Error while checking public key used to sign data.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto out; + } + if (!key_is_trusted) { + avb_errorv(full_partition_name, + ": Public key used to sign data rejected.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED; + if (!allow_verification_error) { + goto out; + } + } + } + } + + /* Check rollback index. */ + io_ret = ops->read_rollback_index( + ops, rollback_index_location, &stored_rollback_index); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_errorv(full_partition_name, + ": Error getting rollback index for location.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto out; + } + if (vbmeta_header.rollback_index < stored_rollback_index) { + avb_errorv( + full_partition_name, + ": Image rollback index is less than the stored rollback index.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX; + if (!allow_verification_error) { + goto out; + } + } + + /* Copy vbmeta to vbmeta_images before recursing. */ + if (is_main_vbmeta) { + avb_assert(slot_data->num_vbmeta_images == 0); + } else { + avb_assert(slot_data->num_vbmeta_images > 0); + } + if (slot_data->num_vbmeta_images == MAX_NUMBER_OF_VBMETA_IMAGES) { + avb_errorv(full_partition_name, ": Too many vbmeta images.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } + vbmeta_image_data = &slot_data->vbmeta_images[slot_data->num_vbmeta_images++]; + vbmeta_image_data->partition_name = avb_strdup(partition_name); + vbmeta_image_data->vbmeta_data = vbmeta_buf; + /* Note that |vbmeta_buf| is actually |vbmeta_num_read| bytes long + * and this includes data past the end of the image. Pass the + * actual size of the vbmeta image. Also, no need to use + * avb_safe_add() since the header has already been verified. + */ + vbmeta_image_data->vbmeta_size = + sizeof(AvbVBMetaImageHeader) + + vbmeta_header.authentication_data_block_size + + vbmeta_header.auxiliary_data_block_size; + vbmeta_image_data->verify_result = vbmeta_ret; + + /* Now go through all descriptors and take the appropriate action: + * + * - hash descriptor: Load data from partition, calculate hash, and + * checks that it matches what's in the hash descriptor. + * + * - hashtree descriptor: Do nothing since verification happens + * on-the-fly from within the OS. + * + * - chained partition descriptor: Load the footer, load the vbmeta + * image, verify vbmeta image (includes rollback checks, hash + * checks, bail on chained partitions). + */ + descriptors = + avb_descriptor_get_all(vbmeta_buf, vbmeta_num_read, &num_descriptors); + for (n = 0; n < num_descriptors; n++) { + AvbDescriptor desc; + + if (!avb_descriptor_validate_and_byteswap(descriptors[n], &desc)) { + avb_errorv(full_partition_name, ": Descriptor is invalid.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + switch (desc.tag) { + case AVB_DESCRIPTOR_TAG_HASH: { + AvbSlotVerifyResult sub_ret; + sub_ret = load_and_verify_hash_partition(ops, + requested_partitions, + ab_suffix, + allow_verification_error, + descriptors[n], + slot_data); + if (sub_ret != AVB_SLOT_VERIFY_RESULT_OK) { + ret = sub_ret; + if (!allow_verification_error || !result_should_continue(ret)) { + goto out; + } + } + } break; + + case AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: { + AvbSlotVerifyResult sub_ret; + AvbChainPartitionDescriptor chain_desc; + const uint8_t* chain_partition_name; + const uint8_t* chain_public_key; + + /* Only allow CHAIN_PARTITION descriptors in the main vbmeta image. */ + if (!is_main_vbmeta) { + avb_errorv(full_partition_name, + ": Encountered chain descriptor not in main image.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + if (!avb_chain_partition_descriptor_validate_and_byteswap( + (AvbChainPartitionDescriptor*)descriptors[n], &chain_desc)) { + avb_errorv(full_partition_name, + ": Chain partition descriptor is invalid.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + if (chain_desc.rollback_index_location == 0) { + avb_errorv(full_partition_name, + ": Chain partition has invalid " + "rollback_index_location field.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + chain_partition_name = ((const uint8_t*)descriptors[n]) + + sizeof(AvbChainPartitionDescriptor); + chain_public_key = chain_partition_name + chain_desc.partition_name_len; + + sub_ret = load_and_verify_vbmeta(ops, + requested_partitions, + ab_suffix, + allow_verification_error, + toplevel_vbmeta_flags, + chain_desc.rollback_index_location, + (const char*)chain_partition_name, + chain_desc.partition_name_len, + chain_public_key, + chain_desc.public_key_len, + slot_data, + NULL /* out_algorithm_type */); + if (sub_ret != AVB_SLOT_VERIFY_RESULT_OK) { + ret = sub_ret; + if (!result_should_continue(ret)) { + goto out; + } + } + } break; + + case AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: { + const uint8_t* kernel_cmdline; + AvbKernelCmdlineDescriptor kernel_cmdline_desc; + bool apply_cmdline; + + if (!avb_kernel_cmdline_descriptor_validate_and_byteswap( + (AvbKernelCmdlineDescriptor*)descriptors[n], + &kernel_cmdline_desc)) { + avb_errorv(full_partition_name, + ": Kernel cmdline descriptor is invalid.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + kernel_cmdline = ((const uint8_t*)descriptors[n]) + + sizeof(AvbKernelCmdlineDescriptor); + + if (!avb_validate_utf8(kernel_cmdline, + kernel_cmdline_desc.kernel_cmdline_length)) { + avb_errorv(full_partition_name, + ": Kernel cmdline is not valid UTF-8.\n", + NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + /* Compare the flags for top-level VBMeta struct with flags in + * the command-line descriptor so command-line snippets only + * intended for a certain mode (dm-verity enabled/disabled) + * are skipped if applicable. + */ + apply_cmdline = true; + if (toplevel_vbmeta_flags & AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED) { + if (kernel_cmdline_desc.flags & + AVB_KERNEL_CMDLINE_FLAGS_USE_ONLY_IF_HASHTREE_NOT_DISABLED) { + apply_cmdline = false; + } + } else { + if (kernel_cmdline_desc.flags & + AVB_KERNEL_CMDLINE_FLAGS_USE_ONLY_IF_HASHTREE_DISABLED) { + apply_cmdline = false; + } + } + + if (apply_cmdline) { + if (slot_data->cmdline == NULL) { + slot_data->cmdline = + avb_calloc(kernel_cmdline_desc.kernel_cmdline_length + 1); + if (slot_data->cmdline == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } + avb_memcpy(slot_data->cmdline, + kernel_cmdline, + kernel_cmdline_desc.kernel_cmdline_length); + } else { + /* new cmdline is: <existing_cmdline> + ' ' + <newcmdline> + '\0' */ + size_t orig_size = avb_strlen(slot_data->cmdline); + size_t new_size = + orig_size + 1 + kernel_cmdline_desc.kernel_cmdline_length + 1; + char* new_cmdline = avb_calloc(new_size); + if (new_cmdline == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto out; + } + avb_memcpy(new_cmdline, slot_data->cmdline, orig_size); + new_cmdline[orig_size] = ' '; + avb_memcpy(new_cmdline + orig_size + 1, + kernel_cmdline, + kernel_cmdline_desc.kernel_cmdline_length); + avb_free(slot_data->cmdline); + slot_data->cmdline = new_cmdline; + } + } + } break; + + /* Explicit fall-through */ + case AVB_DESCRIPTOR_TAG_PROPERTY: + case AVB_DESCRIPTOR_TAG_HASHTREE: + /* Do nothing. */ + break; + } + } + + if (rollback_index_location >= AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS) { + avb_errorv( + full_partition_name, ": Invalid rollback_index_location.\n", NULL); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA; + goto out; + } + + slot_data->rollback_indexes[rollback_index_location] = + vbmeta_header.rollback_index; + + if (out_algorithm_type != NULL) { + *out_algorithm_type = (AvbAlgorithmType)vbmeta_header.algorithm_type; + } + +out: + /* If |vbmeta_image_data| isn't NULL it means that it adopted + * |vbmeta_buf| so in that case don't free it here. + */ + if (vbmeta_image_data == NULL) { + if (vbmeta_buf != NULL) { + avb_free(vbmeta_buf); + } + } + if (descriptors != NULL) { + avb_free(descriptors); + } + return ret; +} + +#define NUM_GUIDS 3 + +/* Substitutes all variables (e.g. $(ANDROID_SYSTEM_PARTUUID)) with + * values. Returns NULL on OOM, otherwise the cmdline with values + * replaced. + */ +static char* sub_cmdline(AvbOps* ops, + const char* cmdline, + const char* ab_suffix, + bool using_boot_for_vbmeta) { + const char* part_name_str[NUM_GUIDS] = {"system", "boot", "vbmeta"}; + const char* replace_str[NUM_GUIDS] = {"$(ANDROID_SYSTEM_PARTUUID)", + "$(ANDROID_BOOT_PARTUUID)", + "$(ANDROID_VBMETA_PARTUUID)"}; + char* ret = NULL; + AvbIOResult io_ret; + + /* Special-case for when the top-level vbmeta struct is in the boot + * partition. + */ + if (using_boot_for_vbmeta) { + part_name_str[2] = "boot"; + } + + /* Replace unique partition GUIDs */ + for (size_t n = 0; n < NUM_GUIDS; n++) { + char part_name[PART_NAME_MAX_SIZE]; + char guid_buf[37]; + + if (!avb_str_concat(part_name, + sizeof part_name, + part_name_str[n], + avb_strlen(part_name_str[n]), + ab_suffix, + avb_strlen(ab_suffix))) { + avb_error("Partition name and suffix does not fit.\n"); + goto fail; + } + + io_ret = ops->get_unique_guid_for_partition( + ops, part_name, guid_buf, sizeof guid_buf); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + return NULL; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_error("Error getting unique GUID for partition.\n"); + goto fail; + } + + if (ret == NULL) { + ret = avb_replace(cmdline, replace_str[n], guid_buf); + } else { + char* new_ret = avb_replace(ret, replace_str[n], guid_buf); + avb_free(ret); + ret = new_ret; + } + if (ret == NULL) { + goto fail; + } + } + + return ret; + +fail: + if (ret != NULL) { + avb_free(ret); + } + return NULL; +} + +static int cmdline_append_option(AvbSlotVerifyData* slot_data, + const char* key, + const char* value) { + size_t offset, key_len, value_len; + char* new_cmdline; + + key_len = avb_strlen(key); + value_len = avb_strlen(value); + + offset = 0; + if (slot_data->cmdline != NULL) { + offset = avb_strlen(slot_data->cmdline); + if (offset > 0) { + offset += 1; + } + } + + new_cmdline = avb_calloc(offset + key_len + value_len + 2); + if (new_cmdline == NULL) { + return 0; + } + if (offset > 0) { + avb_memcpy(new_cmdline, slot_data->cmdline, offset - 1); + new_cmdline[offset - 1] = ' '; + } + avb_memcpy(new_cmdline + offset, key, key_len); + new_cmdline[offset + key_len] = '='; + avb_memcpy(new_cmdline + offset + key_len + 1, value, value_len); + if (slot_data->cmdline != NULL) { + avb_free(slot_data->cmdline); + } + slot_data->cmdline = new_cmdline; + + return 1; +} + +#define AVB_MAX_DIGITS_UINT64 32 + +/* Writes |value| to |digits| in base 10 followed by a NUL byte. + * Returns number of characters written excluding the NUL byte. + */ +static size_t uint64_to_base10(uint64_t value, + char digits[AVB_MAX_DIGITS_UINT64]) { + char rev_digits[AVB_MAX_DIGITS_UINT64]; + size_t n, num_digits; + + for (num_digits = 0; num_digits < AVB_MAX_DIGITS_UINT64 - 1;) { + rev_digits[num_digits++] = (value % 10) + '0'; + value /= 10; + if (value == 0) { + break; + } + } + + for (n = 0; n < num_digits; n++) { + digits[n] = rev_digits[num_digits - 1 - n]; + } + digits[n] = '\0'; + return n; +} + +static int cmdline_append_version(AvbSlotVerifyData* slot_data, + const char* key, + uint64_t major_version, + uint64_t minor_version) { + char major_digits[AVB_MAX_DIGITS_UINT64]; + char minor_digits[AVB_MAX_DIGITS_UINT64]; + char combined[AVB_MAX_DIGITS_UINT64 * 2 + 1]; + size_t num_major_digits, num_minor_digits; + + num_major_digits = uint64_to_base10(major_version, major_digits); + num_minor_digits = uint64_to_base10(minor_version, minor_digits); + avb_memcpy(combined, major_digits, num_major_digits); + combined[num_major_digits] = '.'; + avb_memcpy(combined + num_major_digits + 1, minor_digits, num_minor_digits); + combined[num_major_digits + 1 + num_minor_digits] = '\0'; + + return cmdline_append_option(slot_data, key, combined); +} + +static int cmdline_append_uint64_base10(AvbSlotVerifyData* slot_data, + const char* key, + uint64_t value) { + char digits[AVB_MAX_DIGITS_UINT64]; + uint64_to_base10(value, digits); + return cmdline_append_option(slot_data, key, digits); +} + +static int cmdline_append_hex(AvbSlotVerifyData* slot_data, + const char* key, + const uint8_t* data, + size_t data_len) { + char hex_digits[17] = "0123456789abcdef"; + char* hex_data; + int ret; + size_t n; + + hex_data = avb_malloc(data_len * 2 + 1); + if (hex_data == NULL) { + return 0; + } + + for (n = 0; n < data_len; n++) { + hex_data[n * 2] = hex_digits[data[n] >> 4]; + hex_data[n * 2 + 1] = hex_digits[data[n] & 0x0f]; + } + hex_data[n * 2] = '\0'; + + ret = cmdline_append_option(slot_data, key, hex_data); + avb_free(hex_data); + return ret; +} + +AvbSlotVerifyResult avb_slot_verify(AvbOps* ops, + const char* const* requested_partitions, + const char* ab_suffix, + bool allow_verification_error, + AvbSlotVerifyData** out_data) { + AvbSlotVerifyResult ret; + AvbSlotVerifyData* slot_data = NULL; + AvbAlgorithmType algorithm_type = AVB_ALGORITHM_TYPE_NONE; + AvbIOResult io_ret; + bool using_boot_for_vbmeta = false; + + if (out_data != NULL) { + *out_data = NULL; + } + + slot_data = avb_calloc(sizeof(AvbSlotVerifyData)); + if (slot_data == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + slot_data->vbmeta_images = + avb_calloc(sizeof(AvbVBMetaData) * MAX_NUMBER_OF_VBMETA_IMAGES); + if (slot_data->vbmeta_images == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + slot_data->loaded_partitions = + avb_calloc(sizeof(AvbPartitionData) * MAX_NUMBER_OF_LOADED_PARTITIONS); + if (slot_data->loaded_partitions == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + + ret = load_and_verify_vbmeta(ops, + requested_partitions, + ab_suffix, + allow_verification_error, + 0 /* toplevel_vbmeta_flags */, + 0 /* rollback_index_location */, + "vbmeta", + avb_strlen("vbmeta"), + NULL /* expected_public_key */, + 0 /* expected_public_key_length */, + slot_data, + &algorithm_type); + if (!allow_verification_error && ret != AVB_SLOT_VERIFY_RESULT_OK) { + goto fail; + } + + if (avb_strcmp(slot_data->vbmeta_images[0].partition_name, "vbmeta") != 0) { + avb_assert(avb_strcmp(slot_data->vbmeta_images[0].partition_name, "boot") == + 0); + using_boot_for_vbmeta = true; + } + + /* If things check out, mangle the kernel command-line as needed. */ + if (result_should_continue(ret)) { + /* Fill in |ab_suffix| field. */ + slot_data->ab_suffix = avb_strdup(ab_suffix); + if (slot_data->ab_suffix == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + + /* Add androidboot.vbmeta.device option. */ + if (!cmdline_append_option(slot_data, + "androidboot.vbmeta.device", + "PARTUUID=$(ANDROID_VBMETA_PARTUUID)")) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + + /* Add androidboot.vbmeta.avb_version option. */ + if (!cmdline_append_version(slot_data, + "androidboot.vbmeta.avb_version", + AVB_VERSION_MAJOR, + AVB_VERSION_MINOR)) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + + /* Substitute $(ANDROID_SYSTEM_PARTUUID) and friends. */ + if (slot_data->cmdline != NULL) { + char* new_cmdline; + new_cmdline = sub_cmdline( + ops, slot_data->cmdline, ab_suffix, using_boot_for_vbmeta); + if (new_cmdline == NULL) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + avb_free(slot_data->cmdline); + slot_data->cmdline = new_cmdline; + } + + /* Set androidboot.avb.device_state to "locked" or "unlocked". */ + bool is_device_unlocked; + io_ret = ops->read_is_device_unlocked(ops, &is_device_unlocked); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_error("Error getting device state.\n"); + ret = AVB_SLOT_VERIFY_RESULT_ERROR_IO; + goto fail; + } + if (!cmdline_append_option(slot_data, + "androidboot.vbmeta.device_state", + is_device_unlocked ? "unlocked" : "locked")) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + + /* Set androidboot.vbmeta.{hash_alg, size, digest} - use same hash + * function as is used to sign vbmeta. + */ + switch (algorithm_type) { + /* Explicit fallthrough. */ + case AVB_ALGORITHM_TYPE_NONE: + case AVB_ALGORITHM_TYPE_SHA256_RSA2048: + case AVB_ALGORITHM_TYPE_SHA256_RSA4096: + case AVB_ALGORITHM_TYPE_SHA256_RSA8192: { + AvbSHA256Ctx ctx; + size_t n, total_size = 0; + avb_sha256_init(&ctx); + for (n = 0; n < slot_data->num_vbmeta_images; n++) { + avb_sha256_update(&ctx, + slot_data->vbmeta_images[n].vbmeta_data, + slot_data->vbmeta_images[n].vbmeta_size); + total_size += slot_data->vbmeta_images[n].vbmeta_size; + } + if (!cmdline_append_option( + slot_data, "androidboot.vbmeta.hash_alg", "sha256") || + !cmdline_append_uint64_base10( + slot_data, "androidboot.vbmeta.size", total_size) || + !cmdline_append_hex(slot_data, + "androidboot.vbmeta.digest", + avb_sha256_final(&ctx), + AVB_SHA256_DIGEST_SIZE)) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + } break; + /* Explicit fallthrough. */ + case AVB_ALGORITHM_TYPE_SHA512_RSA2048: + case AVB_ALGORITHM_TYPE_SHA512_RSA4096: + case AVB_ALGORITHM_TYPE_SHA512_RSA8192: { + AvbSHA512Ctx ctx; + size_t n, total_size = 0; + avb_sha512_init(&ctx); + for (n = 0; n < slot_data->num_vbmeta_images; n++) { + avb_sha512_update(&ctx, + slot_data->vbmeta_images[n].vbmeta_data, + slot_data->vbmeta_images[n].vbmeta_size); + total_size += slot_data->vbmeta_images[n].vbmeta_size; + } + if (!cmdline_append_option( + slot_data, "androidboot.vbmeta.hash_alg", "sha512") || + !cmdline_append_uint64_base10( + slot_data, "androidboot.vbmeta.size", total_size) || + !cmdline_append_hex(slot_data, + "androidboot.vbmeta.digest", + avb_sha512_final(&ctx), + AVB_SHA512_DIGEST_SIZE)) { + ret = AVB_SLOT_VERIFY_RESULT_ERROR_OOM; + goto fail; + } + } break; + case _AVB_ALGORITHM_NUM_TYPES: + avb_assert_not_reached(); + break; + } + + if (out_data != NULL) { + *out_data = slot_data; + } else { + avb_slot_verify_data_free(slot_data); + } + } + + if (!allow_verification_error) { + avb_assert(ret == AVB_SLOT_VERIFY_RESULT_OK); + } + + return ret; + +fail: + if (slot_data != NULL) { + avb_slot_verify_data_free(slot_data); + } + return ret; +} + +void avb_slot_verify_data_free(AvbSlotVerifyData* data) { + if (data->ab_suffix != NULL) { + avb_free(data->ab_suffix); + } + if (data->cmdline != NULL) { + avb_free(data->cmdline); + } + if (data->vbmeta_images != NULL) { + size_t n; + for (n = 0; n < data->num_vbmeta_images; n++) { + AvbVBMetaData* vbmeta_image = &data->vbmeta_images[n]; + if (vbmeta_image->partition_name != NULL) { + avb_free(vbmeta_image->partition_name); + } + if (vbmeta_image->vbmeta_data != NULL) { + avb_free(vbmeta_image->vbmeta_data); + } + } + avb_free(data->vbmeta_images); + } + if (data->loaded_partitions != NULL) { + size_t n; + for (n = 0; n < data->num_loaded_partitions; n++) { + AvbPartitionData* loaded_partition = &data->loaded_partitions[n]; + if (loaded_partition->partition_name != NULL) { + avb_free(loaded_partition->partition_name); + } + if (loaded_partition->data != NULL) { + avb_free(loaded_partition->data); + } + } + avb_free(data->loaded_partitions); + } + avb_free(data); +} + +const char* avb_slot_verify_result_to_string(AvbSlotVerifyResult result) { + const char* ret = NULL; + + switch (result) { + case AVB_SLOT_VERIFY_RESULT_OK: + ret = "OK"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_OOM: + ret = "ERROR_OOM"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_IO: + ret = "ERROR_IO"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION: + ret = "ERROR_VERIFICATION"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX: + ret = "ERROR_ROLLBACK_INDEX"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED: + ret = "ERROR_PUBLIC_KEY_REJECTED"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA: + ret = "ERROR_INVALID_METADATA"; + break; + case AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION: + ret = "ERROR_UNSUPPORTED_VERSION"; + break; + /* Do not add a 'default:' case here because of -Wswitch. */ + } + + if (ret == NULL) { + avb_error("Unknown AvbSlotVerifyResult value.\n"); + ret = "(unknown)"; + } + + return ret; +} |